Gagging.

Gagging is a protective reflex to stop unwanted entry into the mouth and oropharynx. Some people have a reduced or absent reflex, while others have a pronounced one. Pronounced gag reflexes can compromise all aspects of dentistry, from the diagnostic procedures of examination and radiography to any form of active treatment. In some patients with marked gagging reflexes, it can lead to avoidance of treatment. Many techniques have been described that attempt to overcome this problem, and a variety of management strategies is necessary to aid the delivery of dental care. This is a review of the etiology of gagging problems, clinical assessment, and their classification and categorization prior to clinical treatment. It discusses as well methods for managing patients with gag reflexes during dental treatment.

Phenobarbital-responsive sialadenosis associated with an esophageal foreign body in a dog.

A 4-year-old Yorkshire terrier was presented for an esophageal foreign body. After removal of the foreign body, clinical signs of gagging, regurgitation, and vomiting continued unabated for >6 weeks. The dog had enlarged submandibular salivary glands that were histologically normal. Treatment with phenobarbital resulted in a rapid and dramatic resolution of clinical signs. After 3 months, the dog was weaned of phenobarbital and was free of any signs of disease 6 months later.

Pharmacodynamics and systemic exposure of esomeprazole in preterm infants and term neonates with gastroesophageal reflux disease.

OBJECTIVE: To characterize the pharmacodynamics and systemic exposure of esomeprazole in 26 preterm infants and term neonates with symptoms of gastroesophageal reflux and pathologic acid exposure. STUDY DESIGN: Enrolled patients received oral esomeprazole 0.5 mg/kg once daily for 7 days. Twenty-four-hour esophagogastric pH-impedance monitoring was performed at baseline and on day 7. Pharmacokinetic analysis was performed on day 7. Symptoms occurring during the baseline and day 7 studies were recorded on a symptom chart. RESULTS: There were no significant differences from baseline to day 7 of therapy in the frequency of bolus reflux, consistency of bolus reflux (liquid, mixed, or gas), extent of bolus reflux, or bolus clearance time. Acid bolus reflux episodes were reduced on therapy (median 30 vs 8, P < .001), as was the reflux index (mean % time esophageal pH < 4, 15.7% vs 7.1%, P < .001). The estimated geometric mean of area under the plasma concentration time curve during the dosing interval and observed maximum plasma concentration was 2.5 micromol x h/L and 0.74 micromol/L, respectively. The number of gastroesophageal reflux symptoms recorded over 24 hours was lower on therapy (median 22 vs 12, P < .05). CONCLUSIONS: In preterm infants and term neonates esomeprazole produces no change in bolus reflux characteristics despite significant acid suppression.

Emetic stimulation inhibits the swallowing reflex in decerebrate rats.

The effects of emetic stimulation on the swallowing reflex were investigated in decerebrated rats. Hypoxia, gastric distension and LiCl administration were used as emetic stimulations. The swallowing reflex was elicited by electrical stimulation of the superior laryngeal nerve (SLN, 20 Hz, 3-5 V, 0.3 ms duration) for 20 s. To examine the effect of hypoxia, nitrogen gas was inhaled under artificial ventilation. There were significantly fewer swallows during a decrease in PO(2) than under air ventilation (p<0.05). The number of swallows during 3-ml stomach distension was significantly lower than that before distension (p<0.05). Intravenous administration of LiCl (100 mg/kg) also significantly reduced the number of swallows (p<0.05). The combination of SLN stimulation and emetic stimuli occasionally produced burst activity of abdominal muscles, which might be associated with the gag reflex. Both the gag and swallowing reflexes are well known to be mediated by the nucleus of the solitary tract. The physiological roles of the gag reflex and the swallowing reflex are considered to be reciprocal. Taken together, these results suggest that emetic stimulation inhibits the swallowing pattern generator via the nucleus of the solitary tract, which in turn facilitates the gag reflex.

Management of exaggerated gag reflex using intravenous sedation in prosthodontic treatment.

The gag reflex is a somatic natural response in which the body attempts to eliminate instruments or agents from the oral cavity by muscle contraction. Some patients suffered from such severe retching that behavioral techniques did not sufficiently reduce gagging in dentistry. In these patients, pharmacological management was thought to be the last alternative to eliminate the reflex. However, the potential of intravenous (IV) sedation as a way to overcome problems in gagging management during prosthodontic (prosthetic) therapy has not been sufficiently explored. We examined the benefit of IV sedation to facilitate prosthodontic treatment for problematic gagging patients intolerable to dental therapy. The subjects were 10 severely retching patients (7 males and 3 females) who received prosthodontic or restorative therapy under propofol IV sedation. The number, location and prognosis of dentures/restorations were reviewed retrospectively. Eight dentures (3 removable and 5 fixed partial dentures) and 22 restorations (18 crowns and 4 inlays) were seated successfully in the oral cavity without serious complications related to IV sedation. The restored teeth were located predominantly in the posterior regions. Throughout the observation period of at least 6 months, no symptoms of postoperative pain or swelling were found. Five of the 10 patients showed improved tolerance to oral inspection, indicating a behavioral adjustment to dental care. In prosthodontic treatment extended to the posterior regions, propofol IV sedation proved useful in managing reflex control.

Efficacy of granisetron for the treatment of postoperative nausea and vomiting in women undergoing breast surgery: a randomised, double-blind, placebo-controlled trial.

BACKGROUND: Women undergoing general anaesthesia for breast surgery are especially at risk of experiencing postoperative nausea and vomiting (PONV). This study was undertaken to assess the efficacy of granisetron, a selective serotonin type 3 receptor antagonist, for the treatment of postoperative nausea and vomiting after breast surgery. DESIGN AND METHODS: This was a prospective, randomised, double-blind, placebo-controlled study carried out in a university-affiliated teaching hospital. The study included women who experienced nausea lasting >10 minutes and/or vomiting during the first 3 hours after recovery from anaesthesia for breast surgery. Patients intravenously received either placebo or granisetron at four different doses (10 microg/kg, 20 microg/kg, 40 microg/kg and 80 microg/kg). Patients were observed for 24 hours after administration of the study drug. MAIN OUTCOME MEASURES AND RESULTS: A total of 100 women were enrolled in this study. Complete control of established PONV, defined as no emetic symptoms and no need for a rescue antiemetic, was observed in 50% of women receiving granisetron 10 microg/kg (p = 0.5 vs placebo), 85% of women receiving granisetron 20 microg/kg (p = 0.009 vs placebo), 90% of women receiving granisetron 40 microg/kg (p = 0.003 vs placebo), and 85% of women receiving granisetron 80 microg/kg (p = 0.009 vs placebo), compared with 45% of placebo recipients. The efficacies of granisetron 20 microg/kg, granisetron 40 microg/kg, and granisetron 80 microg/kg for the treatment of established PONV were superior to that of granisetron 10 microg/kg (all p < 0.05). No serious adverse effects were observed in any group. CONCLUSION: The minimum effective dose of granisetron for the treatment of PONV in women undergoing breast surgery was 20 microg/kg. Increasing the granisetron dose to 80 microg/kg provided no further benefit.

Effects of injecting GABAergic agents into the medullary reticular formation upon swallowing induced by the superior laryngeal nerve stimulation in decerebrate cats.

The purpose of this study was to elucidate the role of the GABAergic system in the medullary reticular formation (MRF) in the control of swallowing. In acutely decerebrated cats (n = 12), swallowing was induced by electrical stimulation (0.3-6 V at 10-20 Hz for 10-20 s every minute) applied to the superior laryngeal nerve (SLN). The stimulus intensity was adjusted so that swallowing was induced two or four times during the period of the stimulation. Bicuculline, a GABA(A) receptor antagonist, was then injected (0.10-0.15 microl, 5 mM) into the MRF through a stereotaxically placed glass micropipette. In a total of 62 injections, 19 injections (30.6%) increased the frequency of SLN-induced swallowing when it was injected into the lateral part of the MRF corresponding to the nucleus reticularis parvocellularis (NRPv). In eight of the effective injections (42.1%) which increased the frequency of SLN-induced swallowing, SLN stimulation also induced coughing. With two injections, stimulation of the SLN-induced coughing but not facilitation of swallowing. On the other hand, an injection of 0.10-0.15 microl of 5 mM muscimol, a GABA(A) receptor agonist, into the NRPv decreased the frequency of SLN-induced swallowing. These results suggest that the NRPv neurons which are responsible for evoking swallowing are under the tonic inhibitory control of the GABAergic system.

Mutation of the feh-1 gene, the Caenorhabditis elegans orthologue of mammalian Fe65, decreases the expression of two acetylcholinesterase genes.

The molecular adaptor Fe65 is one of the cytosolic ligands of the Alzheimer's beta-amyloid precursor protein (APP), and this complex is believed to play important roles in mammalian cells. Upon cleavage of APP by specific processing activities, the complex between Fe65 and the APP intracellular domain (AICD) translocates to the nucleus. Experimental evidence suggests that the Fe65-AICD complex regulates gene transcription. In Caenorhabditis elegans the orthologue of the Fe65 gene, feh-1, regulates pharyngeal activity. In fact, the rate of pharyngeal contraction is increased following transient or stable suppression of the feh-1 gene expression. Here we show that the increased contraction rate of the pharynx in feh-1 mutant worms is associated to decreased acetylcholinesterase activity. The decreased activity is accompanied by reduced expression of ace-1 and ace-2 transcripts, coding for the two major acetylcholinesterase activities in the nematode. These results indicate a target of the regulatory mechanisms based on the Fe65-APP complex that could be relevant for the pathogenesis of Alzheimer's disease.

Gagging prevention using nitrous oxide or table salt: a comparative pilot study.

PURPOSE: The objective of this study was to compare two methods for reducing gagging induced by stimulation of the soft palate: table salt and nitrous oxide inhalation sedation. MATERIALS AND METHODS: Fifteen healthy volunteers, eight men and seven women with a mean age of 20.6 years, were subjected to a gagging event three times using a large tablespoon to stimulate the soft palate: event 1 = spoon alone, event 2 = spoon and table salt on the tip of the tongue with a 30-minute break between events 1 and 2, and event 3 = spoon and nitrous oxide sedation on another day. Time in seconds was measured from the moment the spoon touched the soft palate until gagging was felt using a chronometer held by the subject. RESULTS: The mean time for eliciting the gagging reaction was 7.7 seconds for the spoon alone, 8.9 seconds for the spoon and table salt, and 24.0 seconds for the nitrous oxide sedation. Nitrous oxide inhalation sedation significantly (P < .001) reduced the gagging/retching reaction, whereas there was no significant time difference in gagging reaction between stimulation with the spoon alone or when table salt was added. CONCLUSION: Within the limits of this study, table salt did not seem to reduce the time to triggering the gag reflex, whereas nitrous oxide had a substantial effect.

The use of thiopentone/propofol admixture for laryngeal mask airway insertion.

An admixture of thiopentone and propofol was evaluated against propofol for laryngeal mask airway (LMA) insertion. Eighty-one ASA 1 and 2 18- to 65-year-old patients, premedicated with 7.5 mg midazolam orally were assigned randomly to receive either propofol 1% or an admixture of thiopentone and propofol (1.25% and 0.5% respectively), both at a dose of 0.25 ml x kg(-1). Satisfactory conditions for insertion were achieved with the admixture, which was comparable to propofol (73% vs 85%, P>0.05). There was no statistical difference in the incidence or severity of gagging, coughing, inadequate jaw relaxation and laryngospasm. The incidence of hypotension was lower in the admixture group (51% vs 78%, P=0.02). The duration of apnoea was not different between the admixture and propofol group (mean 103s vs 109s respectively, P>0.05). We conclude that thiopentone/propofol admixture can be a suitable alternative to propofol for LMA insertion, producing less hypotension while allowing cost savings of up to 45%. An admixture of thiopentone and propofol (1.25% and 0.5% respectively) can produce suitable conditions compared to propofol 1%, for laryngeal mask insertion. In addition to cost containment, the admixture also produces less hypotension.

The efficacy and safety of EMLA cream for awake fiberoptic endotracheal intubation.

EMLA Cream (EC; Astra, Westborough, MA) has been widely used as a local anesthetic. Limited safety information is available with respect to the application of EC to the oral mucous membranes. The purpose of this pilot study was to evaluate the efficacy and safety of EC when applied to oral mucosa for fiberoptic intubation. Twenty ASA physical status I-IV patients (11 women and 9 men), 28-57 yr old, who were scheduled for awake, fiberoptic, intubation participated in this open-label study. A total of 4 g of EC was used for 5 min until the patient showed no evidence of a gag reflex (this was evaluated clinically by the patient's acceptance of the William's airway and considered the endpoint for assessing adequate topicalization of the oropharynx). The measured peak plasma concentration of lidocaine or prilocaine did not reach toxic levels in any patient. Methemoglobin levels did not exceed normal values (1.5%) in any patient, and there was no relationship between methemoglobin levels and patient weight, amount of EC used, measured peak plasma concentration, or times to measured peak concentrations of prilocaine or lidocaine. We conclude that EC provided satisfactory topical anesthesia allowing for successful oral fiberoptic intubation in all patients and should be considered a safe alternative for anesthetizing the airway of patients requiring awake oral fiberoptic intubation.

Respiratory sinus arrhythmia and clinical signs of anaesthesia in children.

We have investigated changes in respiratory sinus arrhythmia (RSA) and compared these with clinical signs of anaesthesia in children. Children aged 3-10 yr were anaesthetized by gaseous induction with halothane and nitrous oxide. Multiple heart rate variability (HRV) spectra were obtained by power spectral analysis of continuous epochs of time from before introduction of halothane (baseline) until the pupils were central and fixed (stage 3). Measurement of RSA was performed by integration of the area under the spectral curve within the range of the respiratory frequency +/- 0.15 Hz. In all patients RSA decreased continuously during induction unless stimulation occurred with insertion of an airway. Values of RSA were compared at three times: baseline, loss of pharyngeal tone and stage 3. The decrease in RSA from baseline to loss of pharyngeal tone and from loss of pharyngeal tone to stage 3 was significant (P = 0.003 and P = 0.018, respectively). These results show that RSA can be related to the clinical signs of anaesthesia and has potential as a measure of depth of anaesthesia in children.

Elimination of hypersensitive gagging reaction to dentistry by propofol at subhypnotic doses.

We describe a 44-year-old male patient with severe gagging reaction successfully treated without sedative effect by a continuous infusion of propofol. Propofol at subhypnotic doses seemed to be effective in eliminating hypersensitive gagging reaction to dentistry.

Sympathoexcitatory response to cyclosporin A and baroreflex resetting.

We postulate that the sympathoexcitatory response associated with the immunosuppressive agent cyclosporin A is due to an upward resetting of the arterial baroreflex. We performed studies in conscious intact and sinoaortic-denervated rabbits instrumented with catheters and renal nerve electrodes. In intact rabbits, cyclosporin A (20 mg/kg i.v., 30 minutes) produced significant increases in renal sympathetic nerve activity (100% to 269 +/- 74%, P < .05) but did not increase mean arterial pressure. In intact rabbits, we determined arterial baroreflex curves relating renal sympathetic nerve activity and heart rate to mean arterial pressure by producing ramp increases (intravenous phenylephrine) and decreases (intravenous nitroprusside) in mean arterial pressure. Cyclosporin A treatment produced a shift of the midrange of the baroreflex control of heart rate (78.0 +/- 4.1 to 84.6 +/- 4.7 mm Hg, P < .05) and renal sympathetic nerve activity (74.6 +/- 3.9 to 87.0 +/- 4.8 mm Hg, P < .05). Vehicle administration produced no effects on arterial baroreflex curves relating renal sympathetic nerve activity and heart rate to mean arterial pressure. Compared with vehicle treatment, cyclosporin A reduced the maximum gain of heart rate (-5.6 +/- 0.6 versus -3.1 +/- 0.8 beats per minute per millimeter of mercury, P < .05) but had no effect on the maximum gain of renal sympathetic nerve activity. In conscious sinoaortic-denervated rabbits, cyclosporin A had no effect on mean arterial pressure (95.7 +/- 7.3 to 91.8 +/- 10.8 mm Hg), renal sympathetic nerve activity (100% to 110 +/- 6%). and heart rate (287 +/- 10 to 279 +/- 8 beats per minute). However, when the same sinoaortic-denervated rabbits were anesthetized with sodium pentobarbital, cyclosporin A (20 mg/kg i.v.) produced increases in renal sympathetic nerve activity (100% to 189 +/- 27%). These data indicate (1) that the sympathoexcitatory response to cyclosporin A depends on baroreceptor afferent input in the conscious state and (2) that this response involves an upward resetting of the arterial baroreflex.

Topical lignocaine and thiopentone for the insertion of a laryngeal mask airway; a comparison with propofol.

We assessed conditions for insertion of a laryngeal mask airway in 90 unpremedicated adult patients who received either thiopentone 5 mg.kg-1 preceded by 40 mg of topical lignocaine spray to the posterior pharyngeal wall or propofol 2.5 mg.kg-1 alone in a randomised, single-blinded trial. All patients received fentanyl 1 microgram.kg-1. Gagging, coughing and laryngospasm following laryngeal mask insertion were graded and haemodynamic data and apnoea times were recorded. There were no significant differences between the two groups with regard to the incidence of gagging, coughing and laryngospasm, but the apnoea time was significantly less in the thiopentone group (p < 0.005). The decrease in systolic and diastolic blood pressure, following induction and the insertion of a laryngeal mask with propofol was significantly greater than following thiopentone (p < 0.05--systolic, p < 0.01--diastolic). We conclude that thiopentone preceded by topical lignocaine spray provides conditions for insertion of a laryngeal mask equal to those of propofol, with more haemodynamic stability and a shorter period of apnoea.

Facilitation of laryngeal mask insertion. Effects of lignocaine given intravenously before induction with propofol.

The effects of pretreatment with lignocaine administered intravenously on the insertion of the laryngeal mask airway were investigated in 80 unpremedicated, ASA 1 or 2, adult day-case patients in a randomised, double-blind, placebo-controlled trial. Patients received either intravenous lignocaine 1.5 mg.kg-1 or an equivalent volume of sodium chloride 0.9%. Induction of anaesthesia was achieved with propofol given via a syringe driver at a fixed rate of 600 ml.h-1 until the patient dropped a weighted syringe. No opioid or sedative drugs were given prior to induction. Pain on injection of propofol was recorded. Jaw opening, ease of insertion of the laryngeal mask, coughing, gagging and airway patency were all scored on three-point scales immediately after mask insertion re-attempted. This cycle was continued until success was achieved and the number of such cycles recorded. There were no differences between the lignocaine and control groups with respect to induction dose of propofol, degree of jaw opening, or amount of gagging. Laryngeal mask insertion was facilitated by pretreatment with lignocaine administered intravenously, without an alteration in induction dose of propofol (p < 0.05). Coughing and airway obstruction were both significantly reduced by pretreatment with lignocaine, as was the incidence of failure of insertion requiring deepening of anaesthesia (p < 0.05).

The anti-emetic effects of CP-99,994 in the ferret and the dog: role of the NK1 receptor.

1. The selective NK1 receptor antagonist, CP-99,994, produced dose-related (0.1-1.0 mg kg-1, s.c.) inhibition of vomiting and retching in ferrets challenged with central (loperamide and apomorphine), peripheral (CuSO4) and mixed central and peripheral (ipecac, cisplatin) emetic stimuli. 2. Parallel studies with the enantiomer, CP-100,263 (1 mg kg-1, s.c.), which is > 1,000 fold less potent as a NK1 antagonist, indicated that it was without significant effect against CuSO4, loperamide, cisplatin and apomorphine-induced emesis. Against ipecac, it inhibited both retching and vomiting, expressing approximately 1/10th the potency of CP-99,994. 3. The 5-HT3 receptor antagonist, tropisetron (1 mg kg-1, s.c.) inhibited retching and vomiting to cisplatin and ipecac, but not CuSO4 or loperamide. 4. CP-99,994 (1 mg kg-1, i.v.) blocked retching induced by electrical stimulation of the ventral abdominal vagus without affecting the cardiovascular response, the apnoeic response to central vagal stimulation or the guarding and hypertensive response to stimulation of the greater splanchnic nerves. CP-99,994 (1 mg kg-1, i.v.) did not alter baseline cardiovascular and respiratory parameters and it failed to block the characteristic heart rate, blood pressure and respiratory rate/depth changes in response to i.v. 2-methyl-5-HT challenge (von Bezold-Jarisch reflex). 5. Using in vitro autoradiography, [3H]-substance P was shown to bind to several regions of the ferret brainstem with the density of binding in the nucleus tractus solitarius being much greater than in the area postrema. This binding was displaced by CP-99,994 in a concentration-related manner. 6. In dogs, CP-99,994 (40 micrograms kg-1 bolus and 300 micrograms kg-1 h-1, i.v.) produced statistically significant reductions in vomiting to CuSO4 and apomorphine as well as retching to CuSO4. 7. Together, these studies support the hypothesis that the NK1 receptor antagonist properties of CP-99,994 are responsible for its broad spectrum anti-emetic effects. They also suggest that CP-99,994 acts within the brainstem, most probably within the nucleus tractus solitarius although the involvement of the area postrema could not be excluded.